EP0545049A1 - Mit einer Legierung auf der Grundlage von Al-Zn-Si überzogenes Produkt und Verfahren zur Herstellung desselben - Google Patents

Mit einer Legierung auf der Grundlage von Al-Zn-Si überzogenes Produkt und Verfahren zur Herstellung desselben Download PDF

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Publication number
EP0545049A1
EP0545049A1 EP92117816A EP92117816A EP0545049A1 EP 0545049 A1 EP0545049 A1 EP 0545049A1 EP 92117816 A EP92117816 A EP 92117816A EP 92117816 A EP92117816 A EP 92117816A EP 0545049 A1 EP0545049 A1 EP 0545049A1
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Prior art keywords
alloy
molten bath
article
coat
intermediate layer
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English (en)
French (fr)
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EP0545049B1 (de
Inventor
Masanori C/O Daido Steel Sheet Corp. Takeda
Youichiro Suzuki
Kunio Hayakawa
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S-Tem Ltd
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S-Tem Ltd
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
    • C23C28/021—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material including at least one metal alloy layer
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/024—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by cleaning or etching
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
    • C23C28/023—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only
    • C23C28/025—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only with at least one zinc-based layer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/922—Static electricity metal bleed-off metallic stock
    • Y10S428/9335—Product by special process
    • Y10S428/939—Molten or fused coating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12736—Al-base component
    • Y10T428/1275—Next to Group VIII or IB metal-base component
    • Y10T428/12757—Fe
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12785—Group IIB metal-base component
    • Y10T428/12792—Zn-base component
    • Y10T428/12799—Next to Fe-base component [e.g., galvanized]

Definitions

  • the present invention is directed to an alloy coated product with an Al-Zn-Si base alloy coat including an Al-Zn-Fe-Si alloy layer and a method for making the same.
  • a zinc coating is generally used to provide corrosion resistance to a ferrous-base material.
  • higher corrosion resistance is required to use the ferrous material in severe corrosive environments, e.g., a salt damaged area such as a seaside, an area having an acid rain.
  • many kinds of Al-Zn alloy coats were developed. The demands of the Al-Zn alloy coats are increasing because the Al-Zn alloy coats has more excellent corrosion resistance than the Zn coat.
  • Japanese Patent Publication [KOKOKU] No. 63-63626 describes about a steel wire coated with an Al-Zn alloy containing 3 to 10 wt% of Al. Suzuki et al. Japanese patent early publication [KOKAI] No.
  • 1-263255 also describes about the method of Al-Zn alloy coating, which comprises the steps of dipping an article into a molten bath of Zn at a bath temperature in a range of 480 to 560°C to form an undercoat on the article, and subsequently dipping the undercoat into an alloy molten bath containing at least 1 wt% of Al at a bath temperature in a range of 390 to 460°C to form an Zn-Al alloy coat on the undercoat.
  • the alloy molten bath preferably includes 0.1 to 10 wt% of Al. In case of the Al content less than 0.1%, a desired effect of Al, which is to greatly enhance corrosion resistance of the alloy coat, is not obtained.
  • the alloy molten bath includes more than 10 wt% of Al
  • a typical ferrous metal bath container and the article are given a harmful attack from molten metals of the alloy molten bath.
  • an alloy coat having more excellent corrosion resistance as compared with the Zn-Al alloy coat will be requested.
  • the present invention relates to provide, on an article, an Al-Zn-Si base alloy coat comprising an Al-Zn-Si-Fe alloy layer which has remarkable high corrosion resistance and to a process for forming the alloy coat.
  • the article is made from ferrous base material to provide Fe to the alloy coat.
  • the alloy coat consists essentially of three layers, that is, an interface layer, an intermediate layer and an outer layer.
  • the Al-Zn-Si-Fe alloy layer of the present invention which is the intermediate layer, includes about 55 to 65 wt% of Al, about 5 to 10 wt% of Fe, about 2 to 4 wt% of Fe and about 25 to 35 wt% of Zn, and is also formed into a granular structure or a fine and zonal structure.
  • the intermediate layer has a cross sectional area of 15 to 90 % of the entire cross sectional area of the alloy coat of the present invention.
  • an object of the present invention to provide an Al-Zn-Si base alloy coat including an Al-Zn-Si-Fe alloy layer which has excellent corrosion resistance.
  • the process for forming the alloy coat of the present invention comprises dipping the article into a molten bath of Zn to form, on the article, an undercoat as a reaction layer between Fe of the article and Zn in the molten bath, and then dipping the undercoat into an alloy molten bath of Al, Zn and Si to form the alloy coat on the undercoat.
  • the alloy coat is cooled at an optimum cooling rate in order to obtain a smooth surface and uniformity of the alloy coat after being withdrawn from the alloy molten bath.
  • alloy coat and the process for forming the alloy coat of the present invention will be detailed hereinafter.
  • An Al-Zn-Si base alloy coat including an Al-Zn-Si-Fe alloy layer which has excellent corrosion resistance is made according to a process of the present invention.
  • a steel or a cast iron is used as an article.
  • pre-treatments are performed on a surface of the article in accordance with the following order, alkali cleaning, water cleaning, acid cleaning, water cleaning, and a flux treatment.
  • Each of the pre-treatments is the same way as a general hot-dip Zn coating.
  • the article is cleaned in Alkali solution bath comprising NaOH or NaOH+Na2O 2SiO2 nH2O at a temperature of 70 to 80°C.
  • the water cleaning is done at ambient temperature, and then the article is cleaned in aqueous solution containing hydrochloric acid at ambient temperature.
  • the flux treatment is done in aqueous solution containing zinc chloride and ammonium chloride at a temperature of 80 to 90°C.
  • a hot-dip coating of the present invention essentially consists of first and second hot dipping steps.
  • the most important reason for adopting the two steps of the hot-dip coating is to prevent appearance of the alloy coat of poor quality and also to stably obtain a smooth surface and uniformity of the alloy coat.
  • the first hot dipping step is performed under the conditions described below. After the above pre-treatments have been completed, the article is dipped into the Zn molten bath to form an undercoat on the article. The formation of the undercoat is very important to obtain the smooth surface and the uniformity of the alloy coat. Because the alloy coat is basically formed through a substitutional reaction between the undercoat and molten metals in an alloy molten bath.
  • the Zn molten bath includes at least one metal selected from a group consisting of Al, Si, Mg, Ti, In, Tl, Sb, Nb, Co, Bi, Mn, Na, Ca, Ba, Ni, and Cr.
  • the Zn molten bath includes 0.1 to 5.0 wt% of Al
  • an uniform undercoat is formed on the article because the reaction between Fe of the article and Zn of the Zn molten bath is suitably controlled by Al in the Zn molten bath.
  • the Zn molten bath also includes desirably 0.03 to 2.0 wt% of Ni to obtain the uniform undercoat.
  • An addition of 0.01 to 0.5 wt% of Mg into the Zn molten bath is more effective to obtain the uniform undercoat.
  • a small amount of addition of Ti, Ni, Al and Si for example, 0.1 to 2.0 wt% of Ti, 0.1 to 1.6 wt% of Ni, 0.1 to 1.6 wt% of Al and 0.01 to 0.03 wt% of Si, is preferable to obtain the uniform undercoat.
  • the Zn molten bath is used at a temperature of 430 to 560°C, and preferably 440 to 460°C. In case of the bath temperature higher than 560°C, it is difficult to obtain the uniform undercoat.
  • the article is dipped into the Zn molten bath for 10 to 600 seconds and preferably 15 to 60 seconds.
  • the smooth surface of the alloy coat is not obtained on the undercoat in the second hot dipping step.
  • the article with the undercoat is withdrawn from the Zn molten bath at a withdrawal velocity of 1.0 to 10 m/min and preferably 2 to 4 m/min. In case of the withdrawal velocity slower than 1.0 m/min, the smooth surface of the alloy coat is not formed on the undercoat in the second hot dipping step.
  • the article with the undercoat is also transported from the Zn molten bath to the alloy molten bath within 90 seconds or less and preferably in a range of 10 to 30 seconds. When the article is transported from the Zn molten bath to the alloy molten bath within more than 90 seconds, the smooth surface and the uniformity of the alloy coat is not obtained in the second hot dipping step.
  • the second hot dipping step of the present invention is performed under the conditions described below.
  • the article with the undercoat is dipped into the alloy molten bath essentially consisting of 20 to 70 wt% of Al and preferably 30 to 60 wt% of Al, 0.5 to 4.0 wt% of Si and preferably 2.0 to 3.5 wt% of Si, and the balance of Zn, so that the alloy coat is formed on the undercoat.
  • the Si content in the alloy molten bath is less than 0.5 wt%, or more than 4 wt%, it is difficult to form, on the undercoat, the alloy coat having remarkable high corrosion resistance.
  • the alloy molten bath is used at a temperature of 570 to 670°C and preferably 580 to 610°C.
  • the bath temperature lower than 570°C
  • a large amount of dross is generated in the alloy molten bath.
  • the bath temperature higher than 670°C is adopted in the second hot dipping step
  • the alloy coat having a rough surface is formed on the undercoat.
  • the article with the undercoat is dipped into the alloy molten bath for 5 to 600 seconds and preferably 15 to 45 seconds.
  • the alloy coat having the rough surface is formed on the undercoat. It is further preferred that the alloy molten bath is continuously vibrated to prevent adherence of a floating dross to the alloy coat during the second hot dipping step.
  • the article with the alloy coat When the article with the alloy coat is withdrawn from the alloy molten bath at a withdrawal velocity of 1.0 to 10 m/min and preferably 6 to 9 m/min, no adherence of the floating dross to the alloy coat is observed.
  • the alloy coat is cooled at a particular cooling rate between 670°C and 370°C, and preferably between 610°C and 370°C.
  • the particular cooling rate is -15°C/sec or less and preferably in a range of -3 to -7°C/sec in order to obtain the smooth surface and the uniformity of the alloy coat.
  • the article with the alloy coat is cooled at a rapid cooling rate, for example, more than -30°C/sec, the article is depreciated by discoloration of the alloy coat.
  • alloy coat of the present invention substantially consists of an interface layer, an intermediate layer and an outer layer as shown in FIGS. 1 and 2.
  • the intermediate layer is the Al-Zn-Si-Fe alloy layer having remarkable high corrosion resistance. That is to say, the intermediate layer essentially consists of 25 to 35 wt% of Zn, 55 to 65 wt% of Al, 5 to 10 wt% of Fe and 2 to 4 wt% of Si, and has a cross sectional area of 15 to 90 % of the entire cross sectional area of the alloy coat.
  • the intermediate layer also has a granular structure as shown in FIG. 1, or a fine and zonal structure as shown in FIG. 2.
  • the intermediate layer is formed into the granular structure.
  • the Si content in the alloy molten bath is in a range of 2.1 to 2.8 wt%
  • the intermediate layer is formed into the fine and zonal structure.
  • the fine and zonal structure of the intermediate layer can be also formed by cooling the alloy coat at an optimum cooling rate after the alloy coat has been withdrawn from the alloy molten bath.
  • a hardness of the intermediate layer measured by micro Vickers hardness test is about 150 to 200 Hv.
  • the interface layer is the Al-Zn-Fe-Si alloy layer having different composition from the intermediate layer, that is, the interface layer includes a large amount of Fe and Si and a small amount of Zn compared with the intermediate layer.
  • the interface layer which has a hardness of about 450 to 500 Hv is much harder than the intermediate layer.
  • the outer alloy layer is a solidification layer essentially consisting of Al, Zn, and Si.
  • the outer layer does not always need to obtain excellent corrosion resistance of the present invention.
  • the outer layer of the alloy coat is peeled off to keep an allowance of the bolt by a centrifugation method. By this treatment, the alloy coat essentially consists of the interface layer and the intermediate layer.
  • Each of alloy coats of examples 1 to 6 of the present invention which is Al-Zn-Si base alloy coat including an Al-Zn-Si-Fe alloy layer, was formed on a ferrous base article.
  • the Al-Zn-Si base alloy coat consists essentially of an interface layer, an intermediate layer having excellent corrosion resistance and an outer layer. Therefore, the corrosion resistance of the alloy coat, which varies relative to a ratio of a cross sectional area of the intermediate layer against the entire cross sectional area of the alloy coat, was examined in examples 1-6.
  • the ratio of the cross sectional area of the intermediate layer were determined by observing a cross section of the alloy coat. For example, an alloy coat of example 1 having the ratio of the cross sectional area of the intermediate layer of about 5 % was produced through the following process.
  • a steel sheet which is 100mm wide, 450mm long, 3.2mm high, was used as the ferrous base article.
  • pre-treatments such as alkali cleaning, water cleaning, acid cleaning, and flux treatment were performed on a surface of the article. The treatments were based on the same process as a general hot-dip Zn coating.
  • the article was dipped into the Zn molten bath including 0.005 wt% of Al at a bath temperature of 460°C for 60 seconds to form, on the article, an undercoat which results from a reaction between Fe of the article and Zn in the molten bath.
  • the article with the undercoat was transported from the Zn molten bath to an alloy molten bath within 30 seconds.
  • the article with the undercoat was then dipped into the alloy molten bath consisting of 55 wt% of Al, 1.5 wt% of Si, and the balance of Zn at a bath temperature of 590°C for 40 seconds to form, on the undercoat, the alloy coat including the Al-Zn-Fe-Si alloy layer.
  • the article with the alloy coat was cooled from 590°C to 370°C at a cooling rate of -10°C/sec by air after being withdrawn from the alloy molten bath.
  • alloy coats of examples 2-6 were respectively produced by controlling hot-dip coating conditions such as chemical compositions of the Zn molten bath and/or the alloy molten bath, the dipping time or the cooling rate, etc..
  • the ratio of the cross sectional area of the intermediate layer can be increased by cooling the alloy coat at a slower cooling rate after the article with the alloy coat has been withdrawn from the alloy molten bath.
  • comparative example was formed by the following process. The pre-treatments were performed on the article, and then the article was dipped into the Zn molten bath including 0.005 wt% of Al at the bath temperature of 480°C for 90 seconds. Therefore, the article of comparative example were coated only with the undercoat essentially consisting of Zn and Fe.
  • the undercoat ordinary has a plurality of crystal phases, e.g., ⁇ phase consisting of a pure Zn and ⁇ phase consisting of a Zn-Fe alloy, etc.. More details about the hot-dip coating conditions for producing examples 1-6 and comparative example are shown on TABLE 1.
  • TABLE 2 shows chemical composition of each layer of examples 1-6 analyzed by electron probe micro analysis (EPMA). Results of the EPMA indicate that the chemical composition of the intermediate layer essentially consists of about 55 to 65 wt% of Al, 25 to 35 wt% of Zn, 5 to 10 wt% of Fe, and 2 to 4 wt% of Si.
  • the interface layer is the Al-Zn-Fe-Si layer having different composition from the intermediate layer, that is, the interface layer includes a large amount of Fe and Si and a small amount of Zn compared with the intermediate layer. Therefore, it suggests that the interface layer results from a preferential alloy reaction between Fe, which is included in the article and the undercoat, and Al and Si which are included in the molten metals of the alloy molten bath.
  • the outer layer includes a small amount of Fe and Si compared with the intermediate layer. It suggests that the outer layer is formed by a solidification of molten metals of the alloy molten bath without the preferential alloy reaction.
  • the cross sections of the alloy coats of examples 1-6 observed by electron microscope are also shown in FIGS.
  • results of the corrosion tests of JIS H8502 and the salt spray test with the acetic acid are shown on TABLES 3 and 4, respectively.
  • the results indicate that the corrosion resistance of the alloy coat of the present invention depends on the ratio of the cross sectional area of the intermediate layer against the entire cross sectional area of the alloy coat, that is, as the ratio of the cross sectional area of the intermediate layer increases, the alloy coat shows more excellent corrosion resistance.
  • the results also indicate that no red rust is generated on the alloy coat having the ratio of the cross sectional area of the intermediate layer of more than 40%, even after the alloy coat is exposed in the sulfurous acid gas for 1200 hours, or in the salt spray with the acetic acid for 3000 hours.
  • the salt spray test of JIS Z2371 is in progress. However, no red rust is observed on all examples 1-6, even after the alloy coat was exposed in the salt spray for 5000 hours.
  • a surface roughness of the alloy coat is improved by utilizing a Zn molten bath including a small amount of additive element. Therefore, an effect of the additive element into the Zn molten bath for improving the surface roughness of the alloy coat was examined in examples 7-14.
  • the undercoats of examples 7-14 were formed on the articles by dipping the articles into Zn molten bathes, respectively, including different additive elements such as Ni, Ti, Al and Mg. Then, each of the undercoats was dipped into an alloy molten bath to form the alloy coat on the undercoat. More details about hot-dip coating conditions for producing examples 7-14 are shown in TABLE 5. Cross sections of the alloy coats of examples 7-14 observed by the electron microscope are also shown in FIGS.
  • each of the alloy coats of examples 8-14 has a smooth surface equal to, or better than the alloy coat which was formed through dipping the article into a Zn molten bath including 0.01 wt% of Al of example 7.
  • the three corrosion tests of examples 1-6 were also performed in examples 7-14. All alloy coats of examples 7-14 demonstrated excellent corrosion resistance without generation of red rust, even after being exposed in the sulfurous acid gas for 480 hours, or in the salt spray test for 5000 hours, or in the salt spray test with the acetic acid for 2500 hours.
  • the surface roughness of the alloy coat is also improved by varying hot-dip coating conditions. Therefore, bath temperature and bath composition of the Zn molten bath for improving the surface roughness of the alloy coat were examined in examples 15-20. After the pre-treatments were performed on the articles, the undercoats of examples 15-17 were formed on the articles by dipping the articles into a Zn molten bath including 0.01 wt% of Al at different bath temperatures, respectively. Then, each of the undercoats was dipped into an alloy molten bath consisting of 55 wt% of Al, 1.6 wt% of Si and the balance of Zn to form the alloy coat on the undercoat. More details about hot-dip coating conditions for producing examples 15-17 are shown in TABLE 6.
  • FIGS. 17-19 Cross sections of the alloy coats of examples 15-17 observed by the electron microscope are shown in FIGS. 17-19, respectively.
  • the observations of examples 15-17 indicate that the surface roughness of the alloy coat depends on the bath temperature of the Zn molten bath, that is, higher the bath temperature, more rough the surface of the alloy coat as shown in FIGS. 18 and 19. Therefore, when the Zn molten bath including 0.01 wt% Al is utilized to form the undercoat, the bath temperature of the Zn molten bath of about 450°C is preferable to obtain the alloy coat having the smooth surface.
  • the undercoats of examples 18-20 were formed by dipping the articles into a Zn molten bath including 0.5 wt% Al and 0.5 wt% of Ni at different temperatures, respectively.
  • each of the undercoats was dipped into the alloy molten bath of examples 15-17 to form the alloy coat on the undercoat. More details about hot-dip coating conditions for producing examples 18-20 are shown in TABLE 6.
  • the bath temperature of the Zn molten bath between 450°C and 520°C was useful to obtain the smooth surface of the alloy coat. Therefore, a practical range of bath temperature of a Zn molten bath for forming the smooth surface of the alloy coat is extended by adding a small amount of optimum additive element into the Zn molten bath.
  • the three corrosion tests of examples 1-6 were also performed in examples 15-20. All alloy coats of examples 15-20 demonstrated excellent corrosion resistance without generation of red rust, even after being exposed in the sulfurous acid gas for 480 hours, or in the salt spray test for 5000 hours, or in the salt spray test with the acetic acid for 2500 hours.
  • a micro structure of the intermediate layer of the alloy coat is controlled by the cooling rate of the alloy coat. Therefore, an effect of the cooling rate for controlling to the micro structure of the intermediate layer was examined in examples 21-24.
  • the undercoats were formed on the articles by dipping the articles into a Zn molten bath including 0.3 wt% of Al at 480°C for 60 seconds.
  • the alloy coats of examples 21-24 were formed on the undercoats by dipping the undercoats into an alloy molten bath including 55 wt% of Al, 2.3 wt% of Si and the balance of Zn at 590°C for 30 seconds, and then were cooled at four different cooling rates, respectively, after being withdrawn from the alloy molten bath.
  • FIGS. 23-26 Cross sections of the alloy coats of examples 21-24 observed by the electron microscope are shown in FIGS. 23-26, respectively.
  • the observations indicate that the intermediate layer was formed into a fine and zonal structure when the cooling rate was in a range between -3 and -7 °C/sec, however, when the cooling rate was more than -7 °C/sec, the intermediate layer was mostly formed into a granular structure. Therefore, the cooling rate of the alloy coat which is -7 °C/sec or less is preferable to form the fine and zonal structure of the intermediate layer.
  • the three corrosion tests of examples 1-6 were also performed in examples 21-24.

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  • Mechanical Engineering (AREA)
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  • Coating With Molten Metal (AREA)
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EP92117816A 1991-11-29 1992-10-19 Mit einer Legierung auf der Grundlage von Al-Zn-Si überzogenes Produkt und Verfahren zur Herstellung desselben Expired - Lifetime EP0545049B1 (de)

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JP3316918A JP2777571B2 (ja) 1991-11-29 1991-11-29 アルミニウム−亜鉛−シリコン合金めっき被覆物及びその製造方法

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WO2001055469A1 (de) * 2000-01-28 2001-08-02 Thyssenkrupp Stahl Ag Verfahren zum herstellen eines mit einer zinkbeschichtung versehenen stahlbandes und zinkbeschichtetes stahlband
EP1193323A1 (de) * 2000-02-29 2002-04-03 Nippon Steel Corporation Plattierte stahlprodukte mit hohem korrosionswiderstand und ausgezeichneter formbarkeit und herstellungsverfahren für ein solches produkt
WO2003060180A1 (en) * 2001-12-26 2003-07-24 Zakrytoe Aktsionernoe Obschestvo 'mezhotraslevoe Juridicheskoe Agentstvo 'jurpromkonsalting' Method of applying the coatings from aluminium alloy on cast iron and steel products
CN104611659A (zh) * 2014-07-29 2015-05-13 许昌四达电力设备有限公司 一种螺母镀锌离心装置
US9758853B2 (en) 2013-03-28 2017-09-12 Jfe Steel Corporation Hot-dip Al—Zn alloy coated steel sheet and method for producing same
US11807941B2 (en) 2009-03-13 2023-11-07 Bluescope Steel Limited Corrosion protection with Al/Zn-based coatings
US11840763B2 (en) 2008-03-13 2023-12-12 Bluescope Steel Limited Metal-coated steel strip

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ES2364548T3 (es) 1999-10-07 2011-09-06 Severstal Sparrows Point, Llc. Un producto de acero, producto de acero recubierto y un método de recubrimiento de un producto de acero.
DE10313957A1 (de) * 2002-06-27 2004-01-22 Bwg Gmbh & Co. Kg Verfahren zum Beschichten einer Fläche eines Gleisbauteils sowie Gleisbauteil
KR100676126B1 (ko) * 2005-09-02 2007-02-01 주식회사 한국번디 내식성 도금 강관
WO2009055843A1 (en) * 2007-10-29 2009-05-07 Bluescope Steel Limited Metal-coated steel strip
CN101186998B (zh) * 2007-12-17 2012-01-11 中国电力科学研究院 一种输电线路杆塔长效防腐合金镀层及其制备工艺
JP5600398B2 (ja) * 2009-04-28 2014-10-01 Ｊｆｅ鋼板株式会社 溶融Ｚｎ系めっき鋼板
CN101935789B (zh) * 2009-11-19 2012-03-07 江苏麟龙新材料股份有限公司 含Al-Zn-Si-Mg-RE-Ti-Ni的热浸镀铸铝合金及其制备方法
JP5505132B2 (ja) * 2010-06-30 2014-05-28 新日鐵住金株式会社 溶接性に優れたＡｌ−Ｚｎ系合金めっき鋼材
CN103764865B (zh) * 2012-08-01 2016-08-17 蓝野钢铁有限公司 金属镀覆钢带
KR102153164B1 (ko) * 2017-12-26 2020-09-07 주식회사 포스코 열간 프레스 성형용 도금강판 및 이를 이용한 성형부재
JP7393640B2 (ja) * 2020-01-22 2023-12-07 日本製鉄株式会社 複層めっき鋼板の製造方法

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Publication number Priority date Publication date Assignee Title
WO2001055469A1 (de) * 2000-01-28 2001-08-02 Thyssenkrupp Stahl Ag Verfahren zum herstellen eines mit einer zinkbeschichtung versehenen stahlbandes und zinkbeschichtetes stahlband
EP1193323A1 (de) * 2000-02-29 2002-04-03 Nippon Steel Corporation Plattierte stahlprodukte mit hohem korrosionswiderstand und ausgezeichneter formbarkeit und herstellungsverfahren für ein solches produkt
EP1193323A4 (de) * 2000-02-29 2003-07-16 Nippon Steel Corp Plattierte stahlprodukte mit hohem korrosionswiderstand und ausgezeichneter formbarkeit und herstellungsverfahren für ein solches produkt
WO2003060180A1 (en) * 2001-12-26 2003-07-24 Zakrytoe Aktsionernoe Obschestvo 'mezhotraslevoe Juridicheskoe Agentstvo 'jurpromkonsalting' Method of applying the coatings from aluminium alloy on cast iron and steel products
US11840763B2 (en) 2008-03-13 2023-12-12 Bluescope Steel Limited Metal-coated steel strip
US11807941B2 (en) 2009-03-13 2023-11-07 Bluescope Steel Limited Corrosion protection with Al/Zn-based coatings
US9758853B2 (en) 2013-03-28 2017-09-12 Jfe Steel Corporation Hot-dip Al—Zn alloy coated steel sheet and method for producing same
CN104611659A (zh) * 2014-07-29 2015-05-13 许昌四达电力设备有限公司 一种螺母镀锌离心装置

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JP2777571B2 (ja) 1998-07-16
ES2083644T3 (es) 1996-04-16
US5478600A (en) 1995-12-26
CN1072732A (zh) 1993-06-02
CN1032374C (zh) 1996-07-24
DE69207567D1 (de) 1996-02-22
AU2626892A (en) 1993-06-03
EP0545049B1 (de) 1996-01-10
KR930010208A (ko) 1993-06-22
US5308710A (en) 1994-05-03
KR950007664B1 (ko) 1995-07-14
JPH05148668A (ja) 1993-06-15
DE69207567T2 (de) 1996-05-30
ATE132915T1 (de) 1996-01-15
AU647970B2 (en) 1994-03-31

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